Biorefinery offers the potential to use a wide variety of non-food biomass resources such as agricultural residues, forestry and municipal wastes or dedicated crops such as switchgrass or miscanthus, to produce valuable biochemicals, biomaterials and biofuels.
These compounds may be produced from these vegetal biomass materials through a number of process steps, including biomass degradation and fermentation, using e.g., chemical, physical and/or biological treatments and catalysts. Typically, biorefinery requires pretreatment of the biomass to at least partially hydrolyze the hemicellulose, remove the lignin and de-crystallize the cellulose, so that cellulase enzymes can access their substrate.
Deinococcus bacteria are gram positive bacteria that were firstly isolated in 1956 by Anderson and collaborators. These extremophile organisms are resistant to DNA damage by UV and ionizing radiations or by cross-linking agent (mitomycin C) and are tolerant to desiccation. WO 01/023526 shows the unusual resistance of Deinococcus to radiation and further proposes their engineering and use in bioremediation. WO 2009/063079 shows that Deinococcus bacteria can resist to solvents and transform biomass to generate ethanol. WO 2010/130806 further discloses recombinant Deinococcus strains wherein ethanol biosynthesis genes have been inserted. These recombinant strains do exhibit improved performance in the production of ethanol. WO 2013/092965 also discloses a further generation of improved Deinococcus bacteria, with higher and remarkable biomass degradation and biofuel production properties.
Because the feedstock represents a significant portion of all costs, and in order to obtain high yields of production, an efficient process requires using microorganism strains that have the capacity to metabolize all major sugars found in vegetal biomasses such as glucose, xylose, arabinose, galactose and/or mannose. In particular, cellulosic biomass can comprise 3 to 15% L-arabinose component and improvement in the assimilation of this pentose may significantly decrease the costs of the whole process and increase production yields.
As currently known Deinococcus bacteria are not able to produce ethanol from L-arabinose, there is a need for new L-arabinose metabolic pathway that can be used to produce recombinant Deinococcus bacteria exhibiting efficient conversion of L-arabinose to ethanol or to any other fermentation product or compound of industrial interest.